You will not be able to assist any customer that has filed a charge back with their bank. Inform the customer that their account has been disabled due to a dispute with their financial institution.

Talk Track: It appears there is an active dispute on your transactions. I apologize but my functions with your account are limited. I suggest you reach out to your bank to remove the dispute should you want us to be able to access your account.

You will not be able to assist them until that is resolved. If there are any other active subscriptions with this customer, you should cancel them now.